A conventional driving apparatus uses space vector pulse width modulation (SVPWM) techniques to generate ten PWM signals with a PWM period that has a duration corresponding to a carrier frequency. The conventional driving apparatus controls, based on each PWM signal, operation of a respective one of ten switches thereof between conduction and non-conduction, so as to convert a direct current (DC) input voltage into five output voltage signals for driving a five-phase motor, thereby generating five alternating current (AC) phase currents that flow through the five-phase motor. The phase currents have the same fundamental frequency that is lower than the carrier frequency, and an mth one thereof lags a first one thereof by [72×(m−1)]° in phase, where 2≦m≦5.
In order to reduce the total harmonic distortion of the phase currents, the carrier frequency must be increased (i.e., the duration of the PWM period must be decreased). However, a higher carrier frequency leads to more switchings and thus more switching loss for each switch, and to lower conversion efficiency of the conventional driving apparatus.